Metal DC power Jacks

Frequently asked questions regarding powering your pedal.

DC Jack problem

Postby kdmay » 11 Jun 2010, 12:51

I've done a search and can't find the answer to my question, so I apologise if it is covered elsewhere.

I have built an SHO clone - love it! Does wonders for my clean channel.

Anyway, on to the problem. I am using a Switchcraft 712A DC Jack, as per below. ... zU5g%3d%3d

I have the DC jack ground lug (centre pin) connected to the input jack shorting lug (the one that only grounds when a jack is connected to preserve battery life). I also have the negative battery teminal connected to the same DC jack ground lug.

I then have battery connected to one of the "live" DC jack lugs - the one that terminates the connection when you insert a DC plug. The other DC jack lug is connected to the circuit board.

Works fine with a battery. I tested the DC jack "floating" (i.e. not attached to the enclosure) and when I connected a DC plug (I made up a makeshift DC PS with a battery at the other end that tests 8.5v fine) the DC PS overrides the battery fine and powers up the board (i.e. LED on).

Problem occurs when I attach the DC jack to the enclosure and obviously ground the body of the jack. Now the DC plug does not work.

I tried reversing the "switching". That is, rather than have the insertion of the DC plug terminate the positive terminal of the battery, I had the grounding of the battery being terminated and the positive DC and battery always connected to the circuit board. Same problem occurs.

Help - this is driving me nuts......thankfully the SHO worked first time and sounds amazing. Maybe Mr Vex is watching over me and cursing my use of a DC jack.....!
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Re: DC Jack problem

Postby lolbou » 11 Jun 2010, 13:01

You need a plastic (i.e. insulated) DC jack... :slap:

A classic mistake indeed! I'll look for one of the already existing thread to merge your post (done!!)...
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